1. Let me talk about the contrast between modern sound technology and harmony. For example, "harmony" is like music played by a music box, or music played by multiple music boxes. The technical principle is similar to that of a music box.
Nowadays, mobile phone MP3 has richer sound content, not just one track and one tone. Therefore, after decoding with the audio decoding chip, PA (Power Amplifier) controls the magnitude and waveform of current to drive the electromagnetic coil of the speaker to work and play sound.
Harmony has only a small amount of audio data, so it is monotonous. The more harmonious it is, the better it sounds. (In addition to the buzzer, the speaker can also play and rotate, regardless of the hardware. The comparison speaker is a professional vibrating sound device, but the very old mobile phone is a simple buzzer or speaker. ) 。
2. The reason why the old mobile phone used He Xun was mainly because the hardware didn't use a special audio codec chip at that time, and the speed of its own processor was too low to keep up with the decoding speed of 100 Kb per second. At the same time, it has to deal with many functions, so it can only play music like He Xun with a small amount of data. For our mobile phone driver engineers, its software control is as simple as controlling the gpio port, and the up-and-down levels can be played (for example, it will be a little more complicated than this).
3. He Xuan hardware and hardware principle:
Buzzer (or horn), playing scales is an audio technology with the same playing power but not too much spectrum. Generally speaking, it means playing music of different scales with the same sound (loudness), and the loudness is the same. Buzzer is a very simple vibrating sound device. It has no horn diaphragm and can only make simple sounds.
Multi-chord rotation is a technique of playing multiple audio with low power spectrum. Eight chords and rotations are eight tracks, and all eight tracks have their own loudness music. This kind of music is far less complicated than MP3 and other audio technologies.
He Xuan is a technology used in old or simple electronic devices (* e-cards, a piece of paper and a buzzer, such as a rice cooker that rings when it is cooked, and a yellow car ofo and buzzer that play Merry Christmas and Happy New Year during festivals). When mobile phones first came out, they were all called function machines, so they were not smart phones. At that time, multimedia technology was weak and not scalable. Old mobile phones can only play and rotate music. Because there is no audio decoding chip, mp3 can't be decoded, or the processor speed is low, it's difficult to decode a large amount of audio data quickly, and it's impossible to play out the grand music data in MP3 and other files (tens or even hundreds of K of music data per second), and the encoding technology data of recording is even larger. Professionals who play music technology know PCM format (pulse signal of pure music), which is the real original uncompressed content of recording. The amount of data per second can be as high as 1M, and a song needs more than 200m ~ 1G in 3 minutes, and it is a compressed MP3 and other music files).
Harmony has long been replaced by MP3, MP3 and other multimedia decoders, so Android won't need Harmony for a long time. The hardware technology of harmony is a buzzer, and its principle is similar to that of the music box (the metal bumps on the roller will stir the metal shrapnel in sequence and make a sound).
4. If you see this, congratulations, I'll tell you a technology, the principle of moving iron headphones. The moving iron earphone is actually a bigger buzzer+conductive film, which is actually a little more complicated than what I said, but the principle is like this. The magnetic coil of the horn is replaced by a vibrator, and the large-area vibrating membrane structure disappears.
Author: Qiancheng-Huayou Laochai (Lao Li)
Date: 20 180 103